A primary concern for protection of the ecology in today's society includes protection and conservation of natural resources such as water. Extended periods of drought occurring in various regions of the United States including normally arid regions generally requires severe water use restrictions accompanied by bans on water consuming activities such as lawn or garden watering, car washings, etc., and in many cases water rationing for other domestic uses. Thus domestic water conservation, especially in urban areas, has become increasingly important.
One major source of water overconsumption which has not been satisfactorily regulated to date relates to the amount of fresh water utilized for domestic toilet flushing. Conventional toilet flush tanks are generally arranged so that the operation of the handle actuates a valve lever, causing the entire contents of the tank to be emptied during each flush cycle. Toilets do not in most cases require a complete flush, particularly where liquid or children's wastes are involved, and substantial water conservation can be accomplished by limiting the amount of water used in a toilet flush cycle.
Various methods and devices for limiting the water used for toilet flushing using either conventional ball type or flapper flush valves have been proposed, including placing objects such as bricks in the tank, dual flush systems in which the amount of water used in a flush cycle depends on whether a full or partial flush is selected, etc. However, such methods and devices are either ineffective or relatively complex and expensive, require substantial alteration to the valve itself or the installation of multiple controls inside the tank, external thereto or on the tank handle assembly. Other systems provide two preset discharge volumes, while a discharge volume between these preset flush cycles may provide maximum flush efficiency. In addition, various methods have been proposed in the art for overcoming the buoyancy of a tank ball or flapper valve such as by adding weights thereto to permit termination of the flushing cycle when the handle is released. However, many of these devices require consumer installation or do not meet consumer acceptance. Conventional toilet tanks contain a reservoir of from three to eight gallons of water, and it has been estimated that a family of four using an average of 2 to 2.5 gallons of water per toilet flush could save using the subject invention approximately 20,000 gallons of fresh water per year. Such water saving, when multiplied by the number of toilets in a community or water district, would produce dramatic savings, particularly in multiple dwelling units such as apartments or condominiums, and have a substantial effect on a locality's water resources. In addition to savings in water bills, the use of lesser amounts of water help reduce the overload in sewage systems, septic tanks, and leeching systems.